The Natural Resource Defense Council (NRDC) has released a study, conducted on their behalf by Tetra Tech, which examined the effects of climate change on probable future water supply and demand in the United States. One of the main findings of the study is that one-third of the U.S. counties (> 1,100 counties) will likely face water shortages by 2050.

The Water Supply Sustainbility Index developed by Tetra Tech for the report can be viewed interactively in Google Earth – a link to the data can be found on the NRDC’s website here. You can also turn on and off markers for which counties are top producers of different crops to get a sense of the potential impact of the water shortages. It looks like this (the green dots indicate that the county is one of the top 100 counties for producing vegetables):

The NRDC also released a one-page overview of water shortage risk and crop value in at-risk counties by state (as a PDF here). According to the overview of California’s risk due to climate change:

Percent of CA counties at risk of water shortages: 83%

Total number of CA counties at risk: 48

Total number of CA counties at extreme risk: 19

Total number of CA counties at high risk: 17

Total number of CA counties at moderate risk: 12

The value of all the crops being producing in at-risk CA counties (in $1,000s): $21,585,354